1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>mutex_lock</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="Unreliable Guide To Locking"><link rel="up" href="apiref-mutex.html" title="Chapter&#160;11.&#160;Mutex API reference"><link rel="prev" href="API-mutex-is-locked.html" title="mutex_is_locked"><link rel="next" href="API-mutex-unlock.html" title="mutex_unlock"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span class="phrase">mutex_lock</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-mutex-is-locked.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;11.&#160;Mutex API reference</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-mutex-unlock.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-mutex-lock"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>mutex_lock &#8212; 
2  acquire the mutex
3 </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void __sched <b class="fsfunc">mutex_lock </b>(</code></td><td>struct mutex * <var class="pdparam">lock</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1124731636"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>lock</code></em></span></dt><dd><p>
4     the mutex to be acquired
5    </p></dd></dl></div></div><div class="refsect1"><a name="idp1124733204"></a><h2>Description</h2><p>
6   Lock the mutex exclusively for this task. If the mutex is not
7   available right now, it will sleep until it can get it.
8   </p><p>
9
10   The mutex must later on be released by the same task that
11   acquired it. Recursive locking is not allowed. The task
12   may not exit without first unlocking the mutex. Also, kernel
13   memory where the mutex resides must not be freed with
14   the mutex still locked. The mutex must first be initialized
15   (or statically defined) before it can be locked. <code class="function">memset</code>-ing
16   the mutex to 0 is not allowed.
17   </p><p>
18
19   ( The CONFIG_DEBUG_MUTEXES .config option turns on debugging
20   checks that will enforce the restrictions and will also do
21   deadlock debugging. )
22   </p><p>
23
24   This function is similar to (but not equivalent to) <code class="function">down</code>.
25</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-mutex-is-locked.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="apiref-mutex.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="API-mutex-unlock.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">mutex_is_locked</span>&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;<span class="phrase">mutex_unlock</span></td></tr></table></div></body></html>
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